Apparatus for spraying liquid onto fibers



Dec. 19, 1961 F. F. FULLER ETAL 3,013,525

APPARATUS FOR SPRAYING LIQUID oNTo FIBERS Filed April l0. 1957 Dec. 19,1961 F. F. FULLER x-:TAL 3,013,525

APPARATUS FOR SPRAYING LIQUID ONTO FIBERS Filed April lO, 195? 2Sheets-Sheet 2 y i INVENTORS 66 FRANK F. FULLER JOSEPH M. RULE CHARLESB. THOMPSON ATTORNEY Unite States Patent O 3,013,525 APPARATUS EURSPRAiZlNG LIQUID ON'IO IllBERS Frank F. Fuller, Elizabeth, NJ., andJoseph M. Rule,

Brandywine Hundred, anni Charles B. Thompson, Christiana Hundred, Deh,assignors to E. I. du Pont de Nemours and Company, Wilmington, Del., acorporation of Delaware Filed Apr. 1f), 31957, Ser. No. 651,853 1 Claim.(Ci. 11S- 8) This invention relates to apparatus for spraying liquidsonto fibers, is more particularly directed to apparatus comprising aduct and means ancillary thereto for conveying air-borne fibers therein,said duct forming an inlet into a chamber having a cross-sectional areaabout 9 to 100 times that of the duct, a diffuser in the chamber athwartthe inlet adapted to divert incoming airborne fibers from their normalpath through the chamber and expand the volume they occupy, a spraynozzle within the chamber downstream from the diffuser, preferablyadapted to spray the expanded body of fibers from within, and an outletfrom the chamber, and, optionally, means for Vadmitting air to thechamber tangentially to its sidewall, and is further particularlydirected to processes comprising dispersing fibers in a gas body flowingat a velocity sufficient to suspend them, suddenly expanding, to aboutfrom 9 to 100-fold, the cross-sectional area of the gas body withoutproportionately increasing its forward velocity, directing the gas bodyagainst an obstruction to yits forward flow, whereby to divert thefibers suspended therein from their path of forward travel and to expandthe volume they occupy, spraying a liquid onto the fibers, preferablyfrom a point centrally located in reference to the cross section of themoving gas body, and optionally, directing another gas stream againstthe fibers in the flowing gas body tangentially to its direction ofmotion whereby to divert the fibers further from their path of forwardtravel, and thereafter decreasing the cross-sectional area of the movinggas body.

In the drawings,

FIGURE l illustrates an apparatus of the invention as adapted to thespraying of a liquid onto air-borne cotton fibers at a point between theopeners and the lap-formers, and

FIGURE 2 shows in greater detail the expansion chamber, diffuser, andspray nozzles of a preferred form of the invention, and

FIGURE 3 shows another preferred form of the invention `which includeslouvers on the expansion chamber for admission of auxiliary air, and

FIGURE 4 lillustrates an alternative form of diffuser, and

FIGURE 5 shows a suspended, expanded body of fibers upon which a liquidis being sprayed from a centrally located point, in accordance with amethod of the invention, and

FIGURE 6 shows an apparatus of the invention equipped with an automaticcontrol on the pump supplying the liquid fed to the spray nozzle, saidcontrol being actuated by the flow of air-borne fibers in the inletduct.

When liquids are sprayed onto individual fibers, such as cotton textilefibers prior to forming a lap, the problem is to secure uniformdistribution of an adequate amount of the liquid upon the fibers. Whensaturation is desired or can be tolerated, a mass of the fibers can beimmersed in the liquid, but this requires removal of excess liqu-id,which is often uneconomical. Spraying can be regulated so as to applylesser amounts than saturation; hence no excess liquid is put on and thedisadvantages of immersion are avoided. However, heretofore nopracticable method has been available whereby amounts of liquid up toand approaching the saturation ICC value could be sprayed onto adispersed mass of fibers with relatively uniform distribution.

Conventionally, loose fibers are conveyed pneumatically in ducts fromone operation to another in textile mills. The loose fibers aredispersed in a body of air moving through the ducts with sufficientvelocity to keep the fibers suspended. It has been proposed to sprayvarious treating liquids onto the fibers in such duct work, but effortsto do this have resulted in insufficient penetration of the spraydroplets into the moving body of fibers. The fibers around the outsideedge of the bodythat is, those closest to the duct wall-may beadequately covered if only a small amount of liquid is thus sprayed, butif the amount of spray is increased, the result is not increasedpenetration. Rather, the outside fibers become so wet that they adhereto the duct walls and pile up at elbows, resulting in clogging problemsand non-uniform treatment.

It has also been proposed to insert a constriction into a conveyor duct,Iwhereby the velocity of fibers in the duct is increased, and to spray aliquid onto the fibers while they are passing through the constriction.While this practice increases the proportion of fibers brought intocontact with the spray, it still has the inherent disadvantage that thespray from the nozzle has a relatively short path to the 4-wall of theconstriction, with the result that the wall becomes wet with the sprayliquid. ri'his not only entails loss of spray liquid from its intendedpurpose but also increases the tendency of the fibers to adhere to theconstriction wall. Moreover, the distribution density (i.e., the numberof fibers per unit volume of air) is not decreased because theelongation of the moving body of fibers is only in proportion to thedecrease in cross-sectional area; hence it is just as difficult for thespray to reach remote fibers as Without the constriction.

In contrast to such prior art practices, the processes and apparatus ofthe present invention effect a substantial decrease in distributiondensity of the fibers, and thereby permit fibers remote from the spraynozzle to be reached by the spray, while at the same time the distancefrom the spray nozzle to the wall of the expansion chamber is increasedsufficiently to minimize the chances of the spray liquid reaching thewall. Furthermore, the residence time of fibers in the spray zone issubstantially increased and the path of travel of the fibers through thespray zone is improved, giving better opportunity for contact betweenthe spray `droplets and the fibers. The overall result is that uniformdistribution of the spray onto the fibers is secured with a minimum ofchamber wall wetting and a minimum of agglomerating of the fibers.

Described with particular reference to the embodiments shown in thedrawings, the apparatus of the invention illustrated in FIGURE 1,comprises means 10, such as the conventional breakers and openers of acotton mill, for dispersing fibers in an airstream, a duct 1 1connecting said dispersing means, through inlet 13 to an expansionchamber 12 having -a cross-sectional area about 36 times that of theduct, a diffuser 14 located within the expansion chamber opposite theinlet, the diffuser being in the form of a bell-shaped bafiie plate withthe outer edge of the bell directed away from the inlet, an outlet 16from the expansion chamber connected to a fiber condenser 17 having anexhaust blower 19 adapted to maintain suction through the entire system,and outlet means 18 for discharging treated fibers from the condenser.

FIGURE 2 of the drawings shows another embodiment of the invention inwhich there is an expansion chamber 22 having an inlet 2'3 and an outlet26, a diffuser 24 opposite the inlet and so shaped as to impart a spiralmotion to a gas impinging upon it from the inlet, and

3 spray nozzles 25 and 27 positioned downstream from the diffuser.

FIGURE 3 shows an embodiment of the invention in which there is anexpansion chamber 32 having an inlet 33 and outlet 36, a diffuser 34,and spray nozzle 35, all similar to the corresponding elements of FIGURE1, but also having louvers 30 adapted to admit air to the chamber whenthe system is under suction.

FIGURE 4 shows a particularly effective type of diffuser 44, in whichspiral fins or vanes 41 are provided to impart a spiral motion to anair-stream directed thereon from inlet 43 on expansion chamber 42. Aspray nozzle 45 is located on the downstream side of the diffuser. Ifdesired, the diffuser, can be rotated by turning shaft 46, preferably athigh speed, said shaft being hollow and also serving as inlet means forliquid to nozzle 45.

FIGURE 5 illustrates the practice of a process of the invention. yFibersSi), suspended in an air-stream in duct 51, enter expansion chamber 52through inlet 53. Upon entering the expansion chamber thecross-sectional area of the air-stream is suddenly expanded about 34fold by reason of the larger diameter of the chamber as compared withthe duct. The air-stream is directed against an obstacle to its forwardfiow, viz., diffuser 54. The fibers are thus diverted from their path offorward travel and the volume they occupy is expanded. As the fiberstravel beyond the diffuser, liquid droplets 58 are sprayed upon themfrom spray nozzle 55. The sprayed fibers 56 are then passed out of theexpansion chamber and into a duct of lesser cross-sectional area thanthe chamber through outlet 59.

FIGURE 6 shows an aspect of the invention in which there is an expansionchamber 62 having an inlet duct 61 and an outlet duct 66. In thechamber, opposite the inlet duct, is a diffuser 64, and downstreamtherefrom is a spray nozzle 65. This spray nozzle is adapted to besupplied with a liquid under pressure through supply pipe 60, from pump63, driven by electric motor 67. ln the inlet duct is a finger 68mounted on a pivot 69 in such a manner as to be free to rotate through alimited arc. On an extension of finger 68, outside the duct, is amercury switch 70, so positioned that clockwise rotation of the fingercloses an electric circuit to which the switch is connected, and returnto normal position opens the circuit. This circuit consists of the leads71 to motor 67 and a power source 72, connected in series. In operation7fiow of air-borne fibers from right to left in duct 61 moves finger 68in a clockwise direction, thus causing the spray liquid to be suppliedto nozzle 65. When the flow of fibers is cut off the finger returns toits normal vertical position, thereby cutting off the feed of liquid tothe spray nozzle.

Also shown in FIGURE 6 are nozzles 73 and 74, mounted in in theperiphery of the Aexpansion chamber. Through these nozzles water can besprayed into the chamber to effect humidity control.

It will be understood that the drawings merely illustrate certainspecific embodiments of the invention and that many variations arepossible. Thus, the inlet duct can enter the expansion chamber throughthe side rather than the end and be directed in an upward manner so thatthe upper end of the expansion chamber acts as the diffuser. Again, theshape of the diffusion chamber may differ substantially from any of theembodiments shown in the drawings, provided the relationship of itscross-sectional area to that ofthe inlet duct is as previouslydiscussed.

A number of embodiments ,of the diffuser have been shown in the drawingsbut it will be evident that other modifications can be used. Thefunction of the diffuser is to assist the incoming fibers to spread outin the expansion chamber and occupy substantially `its full volume priorto being sprayed with the treated liquid. The cooperation between thediffuser, the inlet means, andthe expansiOnchamber, furthermore, is suchthat uniform distrii bution of the fibers in the expansion chamber iscncouraged.

The placement of the spray nozzle in the chamber with relation to thediffuser is important. Thus, if the spray from the nozzle is caused toimpinge upon the air-borne fibers as they come from the inlet duct inrelatively closepacked form, the spray is unable to penetrate into themass of fibers and non-uniform application results. Any non-uniformityof application of the spray to the fibers is diligently to be avoidedbecause, in addition to the problems of clogging the duct work andinterfering with proper operation of the fiber-handling machines,nonuniformity of application results in non-uniformity in the propertiesof the treated fibers, which in turn gives unsatisfactory carding,drawing, and spinning operations.

The disposition of the spray nozzles downstream from the diffuser, onthe other hand, permits the spray to impinge on the fibers when they arein the openest possible condition. This insures maximum facility ofsubsequent operations and the development of the maximum beneficialproperties in the treated fiber relative to the amount of spray materialapplied.

The outlet from the expansion chamber ordinarily is a duct ofapproximately the same diameter as the inlet duct, although this is notnecessarily the case. As will be evident from the drawings the expansionchamber is preferably so shaped that below the diffuser there are nodead air spaces where fibers can settle or hang up. A round, bell-shapedor conical bottom in the expansion chamber is, therefore, preferred.

For systems operating under high suction or where the suction fiuctuatesrapidly, it is sometimes desirable to provide means for admitting air tothe expansion chamber tangentially to its side wall. The louvers of FIG-URE 3, for instance, are adapted for this purpose. Admission of airunder these circumstances will assist in obtaining uniform distributionof the fibers in the chamber and can also be used to control the rate ofpassage of the fibers through the chamber by compensating for suddenincreases in the amount of suction.

ln the operation of the spraying processes of this invention, the fibersare first dispersed in a gas body fiowing at a velocity sufficient tosuspend them. This step is conventional in the operation of thepneumatic conveyor systems employed in textile mills. Cotton fibers, forinstance, are received in the form of bales and are passed throughbreakers and openers to effect separation of the fibers. The fibers arethereupon picked up in the air stream of a suction system and conveyedthrough duc-ts, usually of circular cross-section, to the lap-makingequipment. The apparatus of this invention can advantageously beinstalled as part of this pneumatic line.

Upon entering the expansion chamber, the velocity of the air stream isretarded by reason of the greatly expanded cross-sectional area. As thishappens the fibers are diverted from their forward path and the spacesurrounding the individual fibers is increased.

The more openly spaced fibers in the expansion chamber then proceed pastthe diffuser by reason of the continued suction and come into the pathof the liquid spray from the spray nozzle. It will be understood that aplurality of nozzles can be employed for maximum distribution of thespray but ordinarily control of the amount of spray applied to thefibers is somewhat simplified using a single nozzle.

When the liquid being applied to the fibers is a suspension or solutionof a solid in a liquid, there is a danger that a spray-drying effect onthe spray liquid will be encountered. Dilution of the spray willordinarily avoid this but, of course, dilution also makes more difficultIthe problem of getting an adequate amount of spray material onto thefibers without making them too wet to handle. This spray-drying effectis also minimized by atomizing the spray liquid with pressure ratherthan atomizing it by aspirating with air. Moreover, higher nozzlepressures will favor maximum penetration of the spray droplets beforethey dry.

A still further method of offsetting any spray-drying tendency is tooperate at a constant relative humidity, preferably above about 50%.This can be done by spraying moisture into Ithe air stream. Suchmoisture can be added through auxiliary nozzles disposed around theperiphery of the expansion chamber. The latter method of humiditycontrol is preferred because it is much simpler than to attempt tocontrol the humidity of the air entering the suction system.

After the fibers have been sprayed according to a process of theinvention, the cross-sectional area of the moving gas body in which theyare suspended can be dereased in order that the fibers may readily bepurged from the expansion chamber by the forward movement of the air.

It will be understood that in the operation of textile pneumaticconveying systems the feed of fibers may fluctuate or be interrupted.When this occurs the supply of liquid to the spray nozzles in theapparatus of this invention should be cut oif immediately so that theinterior of the expansion chamber does not become wet and the sprayliquid is not wasted.

This is accomplished in an apparatus of the invention by `an automaticcut-off device such as that shown in FIGURE 6 above, in which meanscooperative with the moving body of bers in the inlet duct actuate ashut-olf mechanism on the lpressure system supplying liquid to the spraynozzle. The operation of such cut-0E means cooperatively with the spraymechanism is a valuable aspect of the present invention, and it will beunderstood that means other than those specifically shown in FIG- URE 6can be used. For example, a light beam may be caused to shine across theinlet duct through openings on each side, and impinge upon aphotoelectric cell. In this mechanism the passage of light isinterrupted by fibers flowing through the duct, so that when light isable to strike the photoelectric cell the duct is empty and the flow ofspray liquid to the nozzle is cut off electrically. Still other cut-offmeans will 4be readily apparent from the foregoing description.

The operation of a process of this invention will be better understoodby reference to the following illustrative example.

A liquid spray composition for treating cotton bers was made up asfollows:

A colloidal silica sol was prepared according to the teachings ofBechtold and Snyder, U.S. Patent 2,574,- 902, and having an SiOZzNa2Oweight ratio of 100:1. The sol analyzed: SiO230 percent; Nago- .30percent; water-soluble sulfated non-siliceous ash- 0.10 percent; pH at25 C.9.80, viscosity at 25 C.3.5 centipoises. This sol was stable rforlong periods of time and had a palticle size of about 17 millimicron-s.

The above-prepared colloidal silica sol was mixed with a combination oflow viscosity mineral oil and a small amount of sulfonated mineral oil.One hundred parts of the sol were agitated slowly and a mixture of 16parts cotton conditioning low-viscosity mineral oil having a Sayboltuniversal viscosity of 72.4 seconds at 100 F. and 36.5 seconds at 210 F.and an api gravity of 131.5 and 4 parts of a sulfonated mineral oilhaving a viscosity of 430 centipoises at 25 C. as measured by theBrookfield viscometer and analyzing 71.2 percent carbon, 11.2 percenthydrogen, and 2.77 percent sulfur, was added.

After addition of the oil, the mixture was a uniform emulsion which wasstable for extended periods of time.

The above-described spray emulsion was applied to cotton bers accordingto a process of this invention as follows:

Baled Delta Pine cotton having a fiber length of 1%6 inches and alineness of 4.1 was broken on conventional opening equipment and dumpedinto the hopper of a pneumatic conveyor system. ln the duct ofthepneumatic conveyor, prior to the point at which the cotton reached thepicker hoppers was inserted a spraying apparatus of the type shown inFIGURE 6 of the drawings.

The liquid spray emulsion above-described was sprayed onto the cotton inthis apparatus at a rate calculated to apply 0.4 percent by weight ofsilica calculated as SiO2, based on the weight of cotton. The control onthe amount of application was accomplished by calibrating and settingmetering pumps supplying the spray nozzle, based on cotton ow throughthe unit. Thus, about 20 lbs. of emulsion were applied per 1000 lbs. ofcotton per hour.

The sprayed cotton leaving the spray cham-ber was conveyed pneumaticallyto the picker hoppers. The cotton reaching the picker hoppers was foundto be apparently dry to the touch and showed no tendency to adhere to orwet the picker hopper wall. No apparent dilference in the way in whichthis sprayed material went through conventional picker and lap-makingequipment as compared with unsprayed cotton, was noted. The foregoingcharacteristics indicated that uniform distribution of the liquid spraymaterial had been achieved and an effective amount of silica had beenapplied without making the cotton wet or gummy.

We claim:

In an apparatus of the character described for spraying liquids ontofibers, a duct and means ancillary thereto for suspending and conveyingair-borne fibers therein, said duct forming an inlet in closedconnection with a substantially cylindrical chamber having acrosssectional area about 9 to 100 times that of the duct, a`

diffuser in the chamber athwart the inl-et adapted to divert incomingair-borne fibers from their normal path through the chamber and expandthe volume they o ccupy, a spray nozzle within the chamber downstreamfrom the diffuser, an outlet from said chamber, and means in the inletduct adapted to be actuated by airborne fibers in said duct to admitliquid to said spray nozzle when fibers are moving forward in said ductand to cut ott the ow of liquid to said nozzle when no fibers are movingforward to said duct.

References Cited in the file of this patent UNITED STATES PATENTS2,071,846 Lamb et al. Feb. 23, 1937 2,152,901 Manning Apr. 4, 19392,173,032 Wintermute Sept. l2, 1939 2,324,874 Peters July 20, 19432,568,499 Hood Sept. 18, 19'51 2,725,601 Brenner Dec. 6, 1955 2,749,736Powischill et al. June 12, 1956 2,805,640' Davis et al Sept. 10, 19572,873,483 Lytton Feb. 17, 1959 t FOREIGN PATENTS 179,514 SwitzerlandNov. 17, 1935

